Scattering of atoms and molecules off a barium zirconate surface

• Published in: Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms Beam interactions with materials and atoms, 2001-02, Vol.173 (4), p.503-515
• Main Authors: Jans, S, Wurz, P, Schletti, R, Brüning, K, Sekar, K, Heiland, W, Quinn, J, Leuchtner, R.E
• Format: Article
• Language: English
• Subjects: BaZrO 3; Neutral particle imaging; Particle scattering; Surface ionization
• ISSN: 0168-583X; 1872-9584
• DOI: 10.1016/S0168-583X(00)00421-3

Neutral particle imaging in the low-energy range will, when employed in future spacecraft missions, potentially contribute to enlarging our knowledge about the origin and evolution of our universe. The main difficulty for a neutral particle detector in this energy range is that the incoming neutrals must first be ionized such that they can be mass- and energy-analyzed by conventional methods. In this paper, we report on the first observation of the formation of negatively charged ions upon reflection from a barium zirconate surface. Experiments were performed at two different setups, one of them including a time-of-flight (TOF) measurement of the specularly reflected particles, the other one allows position-resolved detection. We measured high fractions (22–35%) of negative ions and no positive ions when scattering O +, O 0, O 2 + and O 2 0 at 500–3000 eV primary energy per atom off a BaZrO 3 surface. When scattering H +, H 2 + and H 2 0 at 300–1500 eV per atom off the BaZrO 3 surface, 3–5% of the particles were converted into negative ions and 2–8% into positive ions. Our results suggest a complete memory loss of the incident charge state. Scattered molecules dissociated almost completely. The mean energy loss was proportional to the incident particle energy. BaZrO 3 therefore meets the most important requirements for application on a space platform.